1. Field of the Invention
The present invention relates to an image capturing apparatus and a control method thereof.
2. Description of the Related Art
Heretofore, digital still cameras and digital video cameras using an image sensor such as a CCD image sensor or a CMOS image sensor have been widely used. However, the dynamic range (latitude) of these image sensors is narrow compared with silver halide film. For this reason, when capturing a high contrast scene, loss of tone detail in low luminance portions (plugged-up shadows) and loss of tone detail in high luminance portions (blown-out highlights) readily occur.
Systems capable of controlling the dynamic range automatically have been proposed in response to such problems.
For example, in Japanese Patent Laid-Open No. 2005-209012, it is proposed, in the case where it is detected from a captured image that the main subject is backlit or in a high contrast scene, to specify a black saturation point and a white saturation point from a histogram of the image, and perform tone correction such that the brightness of the main subject is appropriate.
Also, in Japanese Patent Laid-Open No. 2004-186876, it is proposed to acquire two types of images with different dynamic ranges using an image sensor disposed with high sensitivity light receiving elements and low sensitivity light receiving elements, by capturing the same scene with the light receiving elements having different sensitivities, and combine these captured images according to a scene analysis result.
However, with the method of Japanese Patent Laid-Open No. 2005-209012, an effect of widening the dynamic range is not obtained, since the points at which the sensor becomes saturated do not change, despite there being an effect of increasing contrast to the eye.
Also, with the method of Japanese Patent Laid-Open No. 2004-186876, an effect of widening the dynamic range is obtained, but there is the problem of the cost involved, since a special image sensor disposed with light receiving elements having different sensitivities needs to be used.